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PRODID:UW-Physics-TWaP
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UID:UW-Physics-Event-2632
DTSTART:20120329T153000
DTEND:20120329T170000
LOCATION:4421 Sterling Hall
SUMMARY:"X-ray Spectroscopy of Massive Stars: Constraints on Stellar Wind Mass-Loss Rates\, Clumping\, and Shock Physics"\, Astronomy Colloquium\, David Cohen\, Swarthmore College
DESCRIPTION:Hot\, luminous\, massive stars are strong sources of soft X-ray emission\, despite their general lack of surface magnetic fields and the associated dynamo activity and MHD processes that heat a corona and explain the X-ray emission of solar-type stars. Since massive stars' surprising discovery as X-ray sources in the late 1970s\, a consensus has emerged that the X-rays are produced in their strong radiation-driven winds. I will show how high-resolution X-ray spectroscopy carried out over the past decade with the Chandra and XMM-Newton satellite observatories has confirmed the basic wind-shock scenario of X-ray production in massive stars and enabled the testing of theoretical models by providing quantitative constraints on the temperature\, spatial distribution\, and kinematics of the X-ray emitting plasma embedded in the stellar wind. I will also discuss how absorption signatures in the X-ray spectra can be used to measure the mass-loss rates of these winds\, and present some initial results that indicate lower mass-loss rates than have been traditionally assumed. When combined with observations in the optical and radio\, these X-ray absorption measurements also provide information about the clumping properties of massive star winds.
URL:http://www.physics.wisc.edu/twap/view.php?id=2632
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